Surface Pressure of Adsorbed Polymer Layers. Effect of Sticking Chain Ends

• Published in: Langmuir 1999-03, Vol.15 (5), p.1802-1811
• Main Authors: Barentin, C, Joanny, J. F
• Format: Article
• Language: English
• Subjects: Applied sciences; Condensed matter: structure, mechanical and thermal properties; Exact sciences and technology; Fluid surfaces and fluid-fluid interfaces; Organic polymers; Physicochemistry of polymers; Physics; Properties and characterization; Surface energy (surface tension, interface tension, angle of contact, etc.); Surface properties; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties)
• ISSN: 0743-7463; 1520-5827
• DOI: 10.1021/la981173t

Using a mean-field theory with two order parameters and scaling laws, we study the properties of adsorbed polymer layers in contact with a pure solvent, at a fixed amount of polymers. We calculate the surface pressure of the polymer Langmuir monolayer, implicitly assuming that the monolayer is insoluble, i.e., that the polymer desorption time is much larger than any other characteristic time, in particular, the equilibrium relaxation time of the layer. This work was motivated by experiments done on poly(ethylene oxide)(PEO) and telechelic PEO adsorbed at the air−water interface that present an adsorbed layer structure at certain densities. Our theoretical results explain quite well the shape of the surface pressure isotherms and the influence of the chain length and of the hydrophobic ends.